1. Field of the Invention
The present invention relates to dual band antennas.
2. Description of the Related Art
A Yagi-Uda antenna is widely known as an antenna providing a high gain in a specific direction and having a directional radiation pattern. The Yagi-Uda antenna includes a radiator formed of a dipole antenna, a director disposed in front of the radiator, and a reflector disposed behind the radiator to improve the front-to-back ratio (F/B ratio) or the forward gain.
The Yagi-Uda antenna can only cover a single frequency band. If dual frequency bands need to be covered, a Yagi-Uda antenna 81 for covering a low frequency band and a Yagi-Uda antenna 82 for covering a high frequency band need to be formed and combined with each other as illustrated in FIGS. 8A and 8B. In FIGS. 8A and 8B, the reference numeral 83 denotes a radiator, the reference numeral 84 denotes a director, and the reference numeral 85 denotes a reflector. The polarization orientation of the Yagi-Uda antennas 81 and 82 is the same as the longitudinal direction of the radiator 83 (width direction of the antennas).